Use of Robust DOB/CDOB Compensation to Improve Autonomous Vehicle Path Following Performance in the Presence of Model Uncertainty, CAN Bus Delays and External Disturbances
Use of Robust DOB/CDOB Compensation to Improve Autonomous Vehicle Path Following Performance in the Presence of Model Uncertainty, CAN Bus Delays and External Disturbances
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DOI：
10.4271/2018-01-1086
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发表时间：
2018-04
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通讯作者：
Haoan Wang;L. Guvenç
中科院分区：
文献类型：
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作者：
Haoan Wang;L. Guvenç
本文选择路径跟踪控制系统作为概念验证演示应用。干扰观测器（DOB）嵌入在转向路径误差自动驾驶回路中，以处理不确定的参数，如车辆质量，车辆速度和道路摩擦系数，并拒绝横摆力矩干扰。嵌入式干扰观测器对车辆模型的补偿迫使其在干扰观测器的带宽内表现得像其名义模型。基于参数空间方法的转向控制器，然后用于优化性能。所提出的方法具有良好的抗干扰性和稳定鲁棒性。可变的时间延迟，从线控转向系统在实际车辆中也可以导致稳定性问题，因为它增加了大的负相位角的植物频率响应，并往往使其不稳定。一个通信干扰观测器（CDOB）为基础的时间延迟补偿方法，不需要确切的知识，这个时间延迟嵌入到转向致动回路来处理这个问题。本文对DOB和CDOB补偿系统的稳定性进行了分析。进行了广泛的模型在环仿真，以测试所设计的干扰观测器和CDOB系统，并显示在存在不确定性，干扰和时间延迟的情况下，减少路径跟踪误差。我们的2017款福特Fusion混合动力研究自动驾驶汽车的验证模型用于仿真分析。仿真结果验证了所提出的DOB和CDOB结构对车辆路径跟踪控制性能的提高。使用经过验证的CarSim模型与传感器和交通的HiL模拟器将在稍后用于验证我们的方法的真实的时间能力。
A path tracking control system is chosen as the proof-of-concept demonstration application in this paper. A disturbance observer (DOB) is embedded within the steering to path error automated driving loop to handle uncertain parameters such as vehicle mass, vehicle velocities and road friction coefficient and to reject yaw moment disturbances. The compensation of vehicle model with the embedded disturbance observer forces it to behave like its nominal model within the bandwidth of the disturbance observer. A parameter space approach based steering controller is then used to optimize performance. The proposed method demonstrates good disturbance rejection and achieves stability robustness. The variable time delay from the steer-by-wire system in an actual vehicle can also lead to stability issues since it adds large negative phase angle to the plant frequency response and tends to destabilize it. A communication disturbance observer (CDOB) based time delay compensation approach that does not require exact knowledge of this time delay is embedded into the steering actuation loop to handle this problem. Stability analysis of both DOB and CDOB compensation system are presented in this paper. Extensive model-in-the-loop simulations were performed to test the designed disturbance observer and CDOB systems and show reduced path following errors in the presence of uncertainty, disturbances and time delay. A validated model of our 2017 Ford Fusion Hybrid research autonomous vehicle is used in the simulation analyses. Simulation results verify the performance enhancement of the vehicle path following control with proposed DOB and CDOB structure. A HiL simulator that uses a validated CarSim model with sensors and traffic will be used later to verify the real time capability of our approach.